Photographic recording equipment



3 Feb. 17, 1948. J. F. EGAN 2,436,103

PHOTOGRAPHIC RECORDING EQUIPMENT Filed Feb. 9, 1946 Patented Feb. 17, 1948 PATEN ing document are photographed simultaneously.

As is well known, in continuous photographic copying machines, the document is moved through a ieedway and past an exposure aperture which is in the field or a camera and illuminated on both sides as it passes the exposure aperture.

The reflected image oi each side or the document is directed by mirrors to the camera lens so that the images appear on the him in the camera in side by side relationship either in abutment or slightly spaced apart. With certain types of doc uments, particularly those which contain printed or written matter on both sides oi relatively thin or translucent paper, ghost or X-ray images appear on the film which are caused by the light transmitted through the document. Various methods have been suggested for eliminating these transmitted images, one oi which is the use of complementary colored filters.

When complementary colored filters are used, a filter is placed adjacent each exposure aperture for illuminating the two sides of the document with complementary colored light, or complementary colored lamps may be used on each side of the exposure aperture. Complementary colored filters are also placed between the mirrors and the camera lens so that the images which are transmitted through the document are eliminated and only the reflected images of the two faces of the document find their way to the camera lens. Although this arrangement eliminates the transmittcd image, the density of the images on the film will not necessarily be the same.

Another factor that enters into the unequal density of the images is the color of the document being photographed. The image or a pinkish or salmon colored document will have a density of ill when illuminated with a red filter or lamp, however, the opposite side which is illuminated with the blue lamp or filter has a density of only do. In a similar manner, the image oi a bluish document which is illuminated with a red lamp or filter has a density oi between or and 0.8, where as the side illuminated with the blue lamp or filter has a density of between 1.0 and 1.1. A similar range of difierences in densities will hold true for filters or lamps of other complementary colors.

The primary object or the present invention is to provide a single filter means adjacent each I exposure aperture in a document copying ma it chine for eliminating the image termed lay the light transmitted through document.

Another object oi the invention to provide a single filter adjacent each exposure aperture in a document copying machine for eliminating the image formed by the light transmitted through the document and which will provide images on the film of equal density.

a iurther ohiect of the invention to provide a filter means comprising two elements of comple mentary colors adjacent each exposure aperture and arranged in inverse relationship tor eliminat ing the image transmitted through the document and for providing images of equal density.

These and. other oloiects oi'the invention will appear from the iollowing specification, the novel features being pointed out in the claims. at the end thereof.

The aforementioned and other objects oi the invention are embodied in a photographic copylng machine which includes a icedway comprising two spaced-apart walls in which there are apertures which are in registry and in the field of a camera, a feeding means for continuously moving the document between the Walls of the feed-way and past the exposure apertures, means for illuminating both sides of the document as it passes the exposure apertures, mirrors for refleeting the images of both sides of the document to the camera lens as well as the transmitted images of both sides, on advancing means for the film which is connected to the feeding means for the document so that both mean" operate in syn chronism, and filters comprising two elements of complementary color adjacent each exposure aperture and arranged in inverse relationship for eliminating the transmitted image from each re= fiected beam.

Coming now to the drawings wherein like ref erence characters denote like parts:

Fig. l is a diagrammatic plan View of a document copying machine emhodying my invention;

Fig. 2 is a diagrammatic-sectional view taken on the line 2-2 at Fig. 1;

Figs. 3, 4, and 5 are sections through a filter showing various ways or constructing a filter comprising complementary elements.

In the embodiment of m invention, the feedway i is formed by the walls 2 and 3 which are mounted between the outer casing wall t, only one of which is shown, and-an intermediate wall 5. The feed rolls 8 and l for advancing the document D are arranged in pairs and mounted between the walls 4 and 5, as shown in Fig. i. The rolls 6 and 'l may be driven in any conventional aeeaios manner, such as by means or a belt drive con nected to a motor or by means or-a geared drive between the rolls and a, motor. The walls 2 and 3 are provided with apertures d to permit the rolls 6 and l to extend therethrough for contacting and moving the document D and with transverse apertures 9 and it in the walls 2 and 23, respectively, which are in registry and in the field of the camera ii. The apertures 9 and iii provide the station'at which the document is photographed as it is moved past the apertures by the rolls 6 and l.

The feed rolls 6 are geared together, as shown at 82 in Fig. l, as are the feed rolls 7. The rolls 6 are provided with a take-oil gear train i8 which is connected to the camera film drive by means of the shaft it and the bevel gears 55. The drives are so geared that the film F in the cam= era ii is advanced continuously with the docu-- ment D and in proper synchronism.

The lamps it provide for illumination of the document as it passes the exposure apertures 9 and iii and may be arranged in banks on either side of the feed rolls 6 and i, as indicated by the dotted lines in Fig. 1.

The mirrors ii and it are placed obliquely in a plane containing the apertures a and it to direct the images of both sides of the document D to the camera lens it. It can be readily appreciated at this point, that ii the document is made of a relatively thin and translucent paper or similar material, the mirror ll will not only receive the reflected image of the left side of the document D, see Fig. 2, but also the image of the right side which will be transmitted through the document D. In a like manner, the mirror I8 will also receive both a reflected and a transmitted image. As pointed out above, with the use of filters of complementary color as previously disclosed, the transmitted images are elim inated, but the density of the reflected images will vary, which results in unequal exposure of the film. The arrangement of complementary filters about to be described not only eliminates the transmitted images but also provides for even density of the images and,- hence, equal exposure.

The filter means is composed of two complementary filters which may be constructed as shown in Figs. 3, 4, and 5. In Fig. 3, the filters 2i and 22 may either be of gelatin or glass which are cemented to a glass plate 23 or, as shown in Fig. 4, may be cemented between the glass plates 24. In Fig. 5, the filter means 20 is made up of glass filters 25 and 26 which are fused together. A narrow opaque strip S may be cemented over the junction of the two filters in order to obtain a sharp and even dividing line between the two elements. The filter colors are chosen so that one will stop about 80-90 percent of the light transmitted by the other and, of course, vice versa. The two colors used should be comple mentary to each other and should transmit light relatively well in that portion of the sensitivity range of the film in which the other transmits very little. For instance, if the filter ill or 25 is red, it will transmit well at the red end of the spectrum and very little in the blue, whereas, if the filter 22 or 26 is blue, it will transmit well at the blue end and very little in the red. However, the filters are chosen so that about one half of the total exposure with white paper is received through each filter.

The filter means 28, when in one of the forms shown in Figs. 3, 4, and 5, are placed adjacent the exposure apertures 9 and iii, as sho n ill 2. However, in mounting the filters in place, the colors must be in inverse order, that is, if a red and blue filter is used and the red filter is placed uppermost on the left side of the eK= posure aperture 9, the blue filter, or the eom= piement of the left side, must be placed upper= most on the right side of the exposure aperture it. With this arrangement two results are obtained; namely, the document as it passes the exposure aperture 9 and it is illuminated by complementary. colored light on each side and the light transmitted through the document is eliminated by the filter on the opposite side: secondly, if colored documents are being photographed, the images will have the same intensity and, hence, the film will receive the same exposure from both images because both sides are photographed through the same colored filters but in opposite order.

In the embodiment of my invention, I have shown it applied to a photographic copying ma= chine in which the document and film are moved continuously; however, those skilled in the art will realize that it is also applicable when the document and'film are stationary during photo= graphing.

I claim:

1. In photographic recording apparatus for simultaneously photographing both sides of a document. the combination with a camera, a document station, means for simultaneously illuml= nating both sides of the document when at said station, and a reflecting means on each side of said station for directing the images of the obverse and reverse sides of the document into said camera and also incidentally directing thereinto undesirable images transmitted through the doc ument, of light filter means adjacent to and on each side of said station, each of said filter means comprising two elements of complementary colors and arranged in inverse relationship to each other for eliminating the images formed by the light transmitted through the document.

2. In photographic recording apparatus for simultaneously photographing both sides of a document, the combination with a camera, a document station, means for simultaneously illuminating both sides of the document when at said station, and a, reflecting means on each side of said station for directing the images of the obverse and inverse sides of the document into said camera and also incidentally directing thereinto undesirable images transmitted through the document, of complementary light filter means adjacent to and on each side of said station, said filter means having one portion for transmitting light to illuminate the document and a second portion complementary in color to said first portion for eliminating the light transmitted through the document from the opposite side and arranged in inverse relationship to each other.

3. In photographic recording apparatus for simultaneously photographing both sides of a document, the combination with a camera, a feedway providing two transverse exposure apertures, said apertures being spaced apart and in registry in the field of said camera, an advancing means fonmoving the photo-sensitive material in said camera in accordance with the movement of the document past said apertures, means for illuminating both sides of the document as itpasses said apertures, and a reflecting means on each side of said station for directing the images oi" the obverse and reverse sides of the document onto the sensitized material in said camera and also incidentally directing thereonto undesirable images transmitted through the document, oi light filter means adjacent to each exposure aper= ture, each of said filter means comprising two elements or complementary colors and arranged in inverse relationship to each other for eliminating the images formed by the light transmitted through the document.

4, In photographic recording apparatus for simultaneously photographing both sides ci a document, the combination with a camera, a Ieedway providing two transverse exposure apertures, said apertures being spaced apart and in registry in the field of said camera, an advancing means for moving the photo-sensitive material in said camera in accordance with the movement of the document past said apertures, means for illuminating both sides or the document as it passes said apparatus, and a reflecting means on each side of said station for directing the images of the obverse and reverse sides of the document onto the sensitized material in said camera and also incidentally directing thereonto undesirable images transmitted through the document, of complementary light filter means adjacent to each exposure aperture and in the path or the reflected image, said filter means having one portion for transmitting light to illuminate the document and a second portion complementary in color to said first portion for eliminating the light transmitted through the document from the opposite side and arranged in inverse relationship to each other.

5. In photographic recording apparatus for simultaneously photographing both sides of a document, the combination with a feedway providing two transverse exposure apertures, said apertures being spaced apart and in registry, a feeding means for continuously moving the document past said exposure apertures, means'ior illuminating both sides of the document as it passes said apertures. an advancing means for moving a photo-sensitive material and adapted to operate in synchronism with the movement of the document, and a reflecting means on each side oi said station for directing the images of the obverse and reverse sides of the document onto the photosensitive material in spaced-apart relationship and also incidentally directing therecnto uncle sirable images transmitted through the docu ment, of light filter means adjacent to each on posure aperture and in the path of the reflected image, each oi said filter means comprising two elements oi complementary colors and arranged in inverse relationship to each other for elimina+- ing the images formed by the light transmitted through said document.

6. In photographic recording apparatus for simultaneously photographing both sides of a document, the combination with a Ieedway providing two transverse exposure apertures, said apertures being spaced apart and in registry, a. feeding means for continuously moving the document past said exposure apertures, means for illuminating both sides of the document as it passes said apertures, an advancing means for moving a photo-sensitive material and adapted to operate in synchronism with the movement of the document, and a reflecting means on each side of said station for directing the images or the obverse and reverse sides of the document onto said photo-sensitive material in spacedapart relationship and also incidentally directing thereto undesirable images transmitted through the document, of complementary light filter means adjacent to each exposure aperture and in the path of the reflected image, said filter means having one portion for transmitting light to illuminate the document and a second portion complementary in color to said first portion for eliminating the light transmitted through the document from the opposite side and arranged in inverse relationship to each other.

JOHN 1'. EGAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name 

